The present invention generally relates to thermoelectric compositions which can be used, for instance, to cool integrated circuit chips in various devices. More particularly, the present invention is directed to thermoelectric compositions comprising transition metal pentatellurides and transition metal chalcogenides.
Thermoelectricity, or the Seebeck effect, is the physical phenomenon used in thermocouples for temperature measurement: a voltage difference is measured for a specific temperature difference. Less common is the use of thermoelectric materials for use in electronic refrigeration or power generation. Recently, there has been a renewed interest in the field of thermoelectrics for these applications. This interest has been primarily driven by the need for new and higher performance thermoelectric materials.
Thermoelectric materials are simply low-power, miniature heat pumps that are small enough to be easily integrated into compact electrical systems. The materials operate under direct current minimizing electrical noise, and can be used for heating or cooling by reversing the direction of current flow.
Thermoelectric energy conversion utilizes the heat generated (as a result of the Peltier effect) when an electric current is passed through a thermoelectric material to provide a temperature gradient (see FIG. 1). Heat is absorbed on the cold side and rejected at the sink, thus providing a refrigeration capability. Conversely, an imposed temperature difference will result in-a voltage or current, that is, power generation on a small scale.
During cooling applications, when a positive DC voltage is applied to the N-type material of the thermoelectric composition, electrons pass from the P-type material. Heat is then absorbed from the cold side of the material causing the temperature to decrease. This heat pumped from the cold side plus the heat generated by the input power is conducted through to the hot side of the composition, where it is dissipated by a heat sink. The degree of cooling achieved is typically proportional to the current and to the number of thermoelectric couples.
The advantages of thermoelectric solid-state energy conversion are compactness, quietness, (no moving parts), and localized heating or cooling. Some applications include cooling of CCDs (charge-coupled devices), infrared detectors, low-noise amplifiers, and computer chips. Such thermoelectric coolers are also very stable and can be used for temperature stabilization of laser diodes or electronic components. Given the harmful effect of standard chlorofluorocarbon and greenhouse refrigeration gases on the environment and the need for small-scale localized cooling in computers and electronics, the field of thermoelectrics is in need of higher performance room-temperature materials than those that currently exist. In addition, as the field of cryoelectronics (utilizing high-transition temperature superconducting electronics) develops, the need for lower temperature (100 to 200 K) and higher performance thermoelectric materials is becoming more prevalent.
Thermoelectric materials are also being considered in the automobile industry for use in the xe2x80x9cnext-generation vehicle.xe2x80x9d Possible uses range from power generation using waste engine heat to seat coolers for comfort or electronic component cooling.
In view of the above, currently, a need exists for new thermoelectric materials for small-scale localized cooling. In particular, a need exists for materials that are more efficient-than conventional compositions.
The present invention recognizes and addresses the foregoing disadvantages, and others of prior art constructions and methods.
Accordingly, it is an object of the present invention to provide thermoelectric compositions for use in thermoelectric devices.
Another object of the present invention is to provide an improved thermoelectric device.
These and other objects of the present invention are achieved by providing a thermoelectric device comprising a thermoelectric composition. According to the present invention, the thermoelectric composition is a pentatelluride. For instance, the pentatelluride can be hafnium pentatelluride or zirconium pentatelluride. Further, the pentatelluride can be doped with various elements, including titanium, selenium, antimony, and mixtures thereof.
In one embodiment, the pentatelluride of the present invention has the following formula:
M1xYxTe5
wherein
X is from 0 to 1
M is Hf or Zr
Y is Ti, Se or Sb.
As described above, the pentatellurides of the present invention can be incorporated into various thermoelectric devices. For most applications, the thermoelectric devices will include a power source for generating a current through the thermoelectric composition. The power source can generate, for instance, a positive DC voltage. The thermoelectric device can be used in many various and different applications.
Other objects, features and aspects of the present invention are discussed in greater detail below.